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61.
Azido Derivatives of the Pentamethylcyclopentadienyl Vanadium(IV)-Fragment. Molecular Structures of the Binuclear Complexes [Cp*VCl(N3)(μ-N3)]2 and [Cp*V(N3)2(μ-N3)]2 The stepwise reaction of Cp*VCl3 with excess trimethylsilyl azide (Me3Si–N3) in solution leads to the paramagnetic, azido-bridged complexes [Cp*VCl2(μ-N3)]2 ( 3 ), [Cp*VCl(N3)(μ-N3)]2 ( 4 ) and [Cp*V(N3)2(μ-N3)]2 ( 5 ) which were characterized by their IR and mass spectra. The azide-rich binuclear complex 5 is also formed if a pentane solution of Cp*V(CO)4 is stirred in the presence of excess Me3Si–N3 in an open vessel. According to the X-ray structure analyses both 4 and 5 are centrosymmetric molecules with a planar V(N)2V four-membered ring. In the absence of free trimethylsilyl azide, solutions of 3 – 5 lose dinitrogen slowly; in the presence of traces of air, 5 is thereby converted to the diamagnetic, oxo-bridged complex [Cp*V(O)(N3)]2(μ-O) ( 6 ). 相似文献
62.
The Insertion of Oxygen Atoms into Ga–Ga and In–In Bonds – Formation of the Monomeric Compounds R2E–O–ER2 [R = CH(SiMe3)2] with Strongly Enlarged Angles E–O–E The tetraalkyldielement compounds R2Ga–GaR2 ( 1 ) und R2In–InR2 ( 2 ) [R = CH(SiMe3)2] reacted with trimethylamine N-oxide by the insertion of oxygen atoms in their element-element single bonds. The products R2E–O–ER2 are monomeric in the solid state due to the high steric shielding by the voluminous bis(trimethylsilyl)methyl groups. As shown by crystal structure determinations, the E–O–E bridges have large angles of 142.7 (E = Ga, 3 ) and 138.6° (E = In, 4 ) and short separations between the oxygen and the coordinatively unsaturated Ga and In atoms. Both products are extremely hygroscopic. 相似文献
63.
Synthesis and Crystal Structure of the Nitrido Complexes [(n‐Bu)4N]2[{(L)Cl4Re≡N}2PtCl2] (L = THF und H2O) and [(n‐Bu)4N]2[(H2O)Cl4Re≡N‐PtCl(μ‐Cl)]2 The threenuclear complex [(n‐Bu)4N]2[{(THF)Cl4Re≡N}2—PtCl2] ( 1a ) is obtained by the reaction of [(n‐Bu)4N][ReNCl4] with [PtCl2(C6H5CN)2] in THF/CH2Cl2. It forms red crystals with the composition 1a · 2 CH2Cl2 crystallizing in the tetragonal space group I41/a with a = 3186.7(2); c = 1311.2(1) pm and Z = 8. If the reaction of the educts is carried out without THF, however under exposure to air the compound [(n‐Bu)4N]2[{(H2O)Cl4Re≡N}2PtCl2] ( 1b ) is obtained as red trigonal crystals with the space group R3 and a = 3628.3(3), c = 1231.4(1) pm and Z = 9. In the centrosymmetric complex anions [{(L)Cl4Re≡N}2PtCl2]2— a linear PtCl2moiety is connected in a trans arrangement with two complex fragments [(L)Cl4Re≡N]— via asymmetric nitrido bridges Re≡dqN‐Pt. For PtII such results a square‐planar coordination PtCl2N2. The linear nitrido bridges are characterized by distances Re‐N = 169.5 pm and Pt‐N = 188.8 pm ( 1a ), respectively, Re‐N = 165.6 pm and Pt‐N = 194.1 pm ( 1b ). By the reaction of [(n‐Bu)4N][ReNCl4] with PtCl4 in CH2Cl2 platinum is reduced forming the heterometallic ReVI/PtII complex, [(n‐Bu)4N]2[(H2O)Cl4Re≡N‐PtCl(μ‐Cl)]2 ( 2 ). It crystallizes in the monoclinic space group C2/c with a = 2012.9(1); b = 1109.0(2); c = 2687.4(4) pm; β = 111.65(1)° and Z = 4. In the central unit ClPt(μ‐Cl)2PtCl of the anionic complex [(H2O)Cl4Re≡N‐PtCl(μ‐Cl)]22— with the symmetry C2 the coordination of the Pt atoms is completed by two nitrido bridges Re≡N‐Pt to nitrido complex fragments [(H2O)Cl4Re≡N] — forming a square‐planar arrangement for the Pt atoms. The distances in the linear nitrido bridges are Re‐N = 165.9 pm and Pt‐N = 190.1 pm. 相似文献
64.
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66.
既有铁路钢桥剩余疲劳寿命的概率性评估 总被引:1,自引:0,他引:1
中国铁路线上大量既有钢桥承受着日益繁重的交通荷载,其疲劳剩余寿命与使用安全已受到桥梁管理部门的高度重视,为避免不必要的维护与更换,应建立合理的既有钢桥使用安全评估方法。在建立能反映铆接钢桥疲劳破坏机理的脆断和韧断概率失效模型基础上,给出了疲劳可靠性分析的极限状态方程,并合理确定了随机变量的参数取值。建立了铆接钢桥构件双角钢概率疲劳破坏模型,基于Monte Carlo算法实现了铆接钢桥构件双角钢疲劳断裂失效概率的计算,编制了相应的概率断裂分析程序DAPFF。进而将概率断裂力学评估方法应用于京九线赣江桥的时变疲劳可靠度分析,并给出了赣江桥概率疲劳剩余寿命评估结果与维护对策。 相似文献
67.
A novel 2-D sheet inorganic-organic hybrid cadmium polymer,[CdBr2(bpdo)]n (bpdo=N,N'-O,O-4,4'-bipyridine) has been hydrothermally synthesized and characterized by elemental analysis,IR and single-crystal X-ray diffraction. The crystal crystallizes in monoclinic,space group C2/c,with a=16.336(3),b=3.9904(5),c=18.479(3),β=91.640(6)°,Mr= 460.40,V=1204.1(3)3,Z=4,Dc=2.540 g/cm3,μ=8.439 mm-1,F(000)=864,R=0.0314 and wR=0.0733 for 1069 observed reflections (I > 2σ(I)). X-ray diffraction reveals that the title compound consists of the 2-D inorganic-organic hybrid sheet constructed from [CdBr2]n chains and bpdo bridges in the packing motif of…ABAB….The title compound exhibits intense blue photoluminescence in the solid state at room temperature. 相似文献
68.
钢箱梁结构在现代大跨度悬索桥体系中较多采用.作为最主要的组成部分之一,其在车辆荷载作用下的受力状态倍受关注.然而目前通过有限元计算还难以获得钢箱梁各细部构造的精确应力值.本文以润扬长江公路大桥南汊悬索桥为背景,介绍了该桥静动载试验中的车辆加载工况和钢箱梁测试截面应力测点的布置等.利用该桥钢箱梁实测应力结果,分析了多种车辆荷载工况下大跨度悬索桥钢箱梁的应力水平及其分布,同时进行了钢箱梁各测试截面受力状态的对比研究,在此基础上总结了大跨度悬索桥钢箱梁结构在车载作用下的受力特点.研究结论为同类钢箱梁的受力状态分析提供了参考依据. 相似文献
69.
Two new dicopper(II) complexes [Cu2L(OAc)2](ClO4)·H2O(1) and [Cu2L(BPP)2]-(ClO4)(2) using an asymmetric dinucleating ligand HL and auxiliary ligands such as acetate(OAc) and bisphenyl phosphate(BPP) have been synthesized and characterized by elemental analysis, IR and single-crystal X-ray diffraction. Complex 1 crystallizes as blue single crystals that belong to the triclinic crystal system and P1 space group, while complex 2 crystallizes in a monoclinic P21/c space group. Single-crystal X-ray diffraction analysis reveals that the two copper ions in complexes 1 and 2 reside within the adjacent ligand compartments and are bridged by the endogenous phenoxo-O from ligand L and the introduction of two desired exogenous carboxylates or phosphates in the bidentate μ-1,3-bridged mode. The coordination geometries of Cu(1) and Cu(2) are both distorted square pyramids. 相似文献
70.
Summary First we give a construction of bridges derived from a general Markov process using only its transition densities. We give sufficient conditions for their existence and uniqueness (in law). Then we prove that the law of the radial part of the bridge with endpoints zero derived from a special multidimensional Ornstein--Uhlenbeck process equals the law of the bridge with endpoints zero derived from the radial part of the same Ornstein--Uhlenbeck process. We also construct bridges derived from general multidimensional Ornstein--Uhlenbeck processes. 相似文献